Refrigerating apparatus



June 16, 1936. H. M. WILLIAMS 2,044,600

REFRIGERATING APPARATUS I Filed July s, 1931 AEYs Patented June 16, 1936mesne assignments, to General Motors Corporation, a corporation ofDelaware Application July 3, 1931, Serial No. 548,612

6Claims.

This invention relates tor'efrigerating appara tus and more particularlyto refrigerator cabinets having insulating walls formed of a, pluralityof spaced sheets of bright metallic foil.

In insulation of spaced sheets of bright metallic foil, the enclosed airspaces are provided for preventing the transmission of heat byconduction, and the sheets of bright metallic foil are provided forpreventing the transmission of heat by radiation. The bright metallicfoil accomplishes this by its reiiecting qualities. Hence in order topreserve the reflecting qualitiesA of this bright metallic foil, it isessential that this foil should not tarnish. I 'I'his tarnishing isordinarily .caused by the condensation of moisture uponthe foil whichusually enters the insulation carried by external air which finds itsway therein.

The objects of my invention include the provision of means forpreventing thebright metallic foil from tarnishing, the provision ofmeans for preventing the access of external air to the foil insulationand for preventing the condensation of moisture upon the foil.

Further objects and advantages of the present invention will be apparentfrom the following description, reference being hadto the accompanyingdrawing, wherein a preferred form of the present invention is` clearlyshown.

In .the drawing: l

Fig. 1 is a vertical sectional view oi a refrigerator embodying theinvention;

Fig.2 is an enlarged sectional'viewof a portion of Fig. 1, and

Fig. 3 is an enlarged sectional view of another portion of Fig. l.

In Fig. l there is shown a refrigerator cabinet 20 having a. machinerycompartment 2| in ,the lower portionand a food storagel compartment 22in the upper portion of the cabinet. Pillars 23 and 24 in the corners ofthe machinery compartment support the walls of the-food storagecompartment. The food storage compartment has an innerwall or shell 25of sheet metal, preferably covered with a suitable substance such asporcelain, and an outer metal wall or shell 26- preferably covered withporcelain; paint, lacquer or other suitable substance. A door 21 isprovided in one wall of the food storage compartment and has on itsinner side a sheet metal member- 28, coated with porcelain, and on itsouter'oide.rr

(Cl. (i2-89) at the four corners of the machinery compartmeut 2|. Acooling unit 30 of any suitable type containing a volatile refrigerantis supported by the top wall of the inner wall or shell 25 within thefood storage compartment. Evaporation of refrigerant within the coolingunit maintains the cooling unit 30' at a. low temperature and coolsthe-cabinet by the convection of air within the food storagecompartment.

In order to prevent the porcelain coating upon the exterior of therefrigerator cabinet from chipping, a chip board 3| is placed againstthe inner side of the outer sheet metal walls 26. By preventingexcessive flexing of the outer sheet metal walls, the chip boardprevents the porcelain from-chipping. nInside of the outer sheet Vmetalwall 26 and the chip board 3|, a relatively thin layer of insulatingmaterial 32 of the fibrous type such as cork is. provided. Thisinsulating material 32 reduces the amount of heat transl mitted byconduction. Between the insulating material 32 and the inner sheet metalshell 25 are provided a plurality of spaced sheets of bright metallicfoil. These sheets of foil 33 are spaced by wooden frame members 36 toprovide air spaces between the sheets of foil. The air spaces betweenthe sheets ofV foil further reduce the transmission of heat byconduction and the sheets of bright metallic foil reduce the amount ofheat transmitted by radiation to a minimum. By such a.construction' theamount of h'eat leakage'into ,the cabinet is exceedingly small. Ifdesired, an additional sheet of foil separated by air spaces from theother sheets of foil and the chip board 3|', may beused instead of thefiber insulation 32. In order to preserve the reflecting qualities ofthe bright metallic foil so as to prevent heat leakage byvradiation, itis necessary to prevent the tarnishing of the bright metallic foil. Thistarnishing has its source in thelleakage of warm` air from theoutside ofthe cabinet to the insulation between the inner and outer shell 25 and26. The cause of this warm air getting into the insulation is due to thefact that it is practically impossible to perfectly seal theinsulation,` and that because of the varying temperature of the walls ofthe cooling unit and the varying barometrlc pressure, due to changingweather conditions, the, air from the exterior of the cabinet isalternately drawn in and forced out-of spaces between the r outer-andinner shells 25' and 26. inasmuch as f theinner shell 25 is made in onepiece, leakage of air from the interior of the cabinet to the insulationdoes not often occur, consequently the air by these causes is ordinarilydrawn from.

'uration point and normally contains a large amount of moisture ascompared to the cold air within the cabinet. When this warm air reachesthe insulatiomit is cooled because of the coldness within the -cabinetand by this cooling the saturation point, that is, the capacity of theair for holding the moisture, is reduced so that dew or moisture iscondensed or deposited in and on the insulation. Thisedew lowers theinsulating value of the brous type of insulation and causes the brightmetallic foil of the foil type of insulation to tarnish and become dullso that its reflecting properties are diminished.

As stated above, the air within the food storage compartment 22 containsa relatively small amount of water vapor therein since the air in itscirculation past the cooling unit has been reduced in temperature sothat the excess moisture in the air has been condensed out oi' the airand as a result, the air contains only a small amount of water vaportherein. By the breathe ing action of the insulation, I supply ,thiscold air containing a relatively small amount of water vapor through thebreathing tube to the insulation between the inner and outershells 25and 26. The tube 35 has its mouth preferably directly beneath thecooling unit so as to draw the coldest air inside of the food storagecompartment. Apertures 3G and 31 are provided in the sheets of metalfoil 33 to provide for the access of air between all the layers ofinsulation to the tube 35. The spacing members 3l are also provided withapertures 38 for providing access of air from the various side panels ofthe cabinet to the breathing tube 35. In order to further prevent atarnishing of the foil, extremely thin coating of beeswax or stearicacid may be applied. Preferably, however, the foil is provided with athin plating of chromium which resists tarnishing to a very high degree.Chromium plated foil resists tarnishing to such a degree that it may beused for insulation without the above described breathing apparatus.Instead of ordinary foil, sheets of paper coated with a suitableadhesive which in turn is coated with aluminum lining bronze by adusting method may be used.

' The door 21 is similarly insulated. The door 21 is provided with athin layer l0 of insulating material of the brous type and a pluralityof layers of bright metallic foil Il suitably spaced by spacing members42 of wood or other suitable material. The sheets of foil are providedwith apertures I3 which provide access; of the air between the layers offoil to a breathing tube 44 which extends beneath the cooling unit.Inasmuch as the zone immediately beneath thecooling unit contains airwhich has just been cooled by the cooling unit, it is preferable thatthe breathing tubes should havegtheir mouths immediately beneath thecooling unit. The foil in the door may be treated similar to the foil inthe other parts of the cabinet as described bovelto prevent tarnishing.`

Thus I have disclosed means for preventing sheets.of bright metallicfoil from tarnishing.

While the form of embodiment of the invention as herein disclosed,constitutes a preferred form,

it is to be understood that other forms might be adopted, all comingwithin the scope of the claims which follow.

What is claimed is as folltws:

1. A refrigerator including a cabinet having inner and outer walls, acooling unit supported within said cabinet, insulation between saidinner and outer walls, said insulation comprising a plurality of spacedsheets of bright metallic foil, and means for preventing said foil fromtarnishing including breathing means having connections with the spacesbetween said sheets for inhaling into said spaces only air dehydrated by.Said cooling unit.

2. A refrigerator including a cabinet having 15 inner and outer walls,`a cooling unit supported within said cabinet, insulation between saidinner and outer walls, said insulation comprising a plurality of spacedsheets of bright metallic foil,

and means for preventing said foil from tarnish` 20 ing includingbreathing means having a tube structure connecting with the spacesbetween said sheets, said tube structure extending immediately beneaththe cooling unit i'or inhaling into said spaces only air dehydrated bysaid cooling unit. 25

3. A refrigerator including a cabinet having inner and outer walls. andinsulation -between said inner and outer walls comprising a plurality ofspacingxmembers, a plurality of sheets of foil mounted `in-'spacedrelation upon the spacing 30 members forming insulation spaces, saidspacing members having passages therethrough and said sheets havingpassages therethrough providing a restricted communication between theinsulation spaces, and breathing means having a single 35 passagecommunicating with the interior of the cabinet and said communicatinginsulation spaces for inhaling into said spaces only'cold dry air fromthe interior of the cabinet.

4. An insulating structure including inner and l outer walls andinsulation between the inner and Outer walls including a plurality oi'sheets held in spaced relation by structural members prvidingsubstantially dead air spaces between the sheets at least some of thesheets having bright 45 metal surfaces, and breathing means forbreathing air into and from the air spaces.

5. An insulating structure including inner and outer walls andinsulation between the inner and outer walls including a plurality ofsheets o! bright metal i'oil held in spaced relation by structuralmembers providing substantially dead air spaces between Ythe sheets offoil, and breathing means communicating with each of the air spaces" 5,'between the sheets of bright metal i'oilfor breathing air into and fromthe air spaces aforesaid. 6. An insulating structure including an-enc1osure formed of spaced inner and outer walls, in-

sulating means between said spaced inner and -outer walls including aplurality oi' sheets held in spaced relation by structural membersproviding substantially dead air spaces between the sheets, at leastsome of the sheets having heat reflecting surfaces, said inner wallsbeing provided an with breathing means for breathing air from theinterior of the enclosure into the space between the inner and outerwalls.

